JP2845812B2 - Electrostatic ink jet recording head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording apparatus for performing recording by attaching toner to a recording medium, and more particularly to a recording head using an electrostatic ink jet recording system.

[0002]

2. Description of the Related Art The non-impact recording method has recently attracted attention in that noise during recording is extremely small to a negligible level. Among them, the ink jet recording method that can record directly on a recording medium at high speed with a simple mechanism and that can record on plain paper is an extremely powerful recording method, and various methods have been proposed so far. Have been. In it, an ink in which toner particles are dispersed in a carrier liquid is used, and a voltage is applied between a needle-like discharge electrode and an electrode provided on the back side of the recording paper facing the discharge electrode. There is a method of recording by causing a color material in ink to fly. An example of the same method will be described with reference to FIGS. The substrate 101 is made of a flat insulating material, and a plurality of ejection electrodes 102 are formed on the surface thereof at intervals equivalent to a desired resolution. Discharge electrode 10
2 is a method in which a conductive material such as Cu or Ni is sputtered on the entire surface of the substrate 101 and then exposed and developed through a mask in which the shape of the discharge electrode 102 is patterned.
01 is formed. The ejection electrodes 102 are formed as independent electrodes, and each ejection electrode 1
02 is connected to a driver (not shown), and a high-voltage pulse is selectively applied during recording. Furthermore, the surface of the substrate 101 on which the ejection electrodes 102 are formed is spin-coated with an insulating coating material so that the ink and the ejection electrodes 102 are insulated. Meniscus forming member 103
Is formed by laminating or spin-coating a photosensitive resist material having an insulating property on the substrate 101 on which the discharge electrodes 102 are formed, and then performing exposure and development through a mask in which the shape of the meniscus forming member 103 is patterned. , And are formed so as to overlap the respective ejection electrodes 102. On the meniscus forming member 103, the cover 10 is located at a position retracted from the front end of the meniscus forming member 103.
4 is attached. The cover 104 is made of an insulating material, and the ink supply port 105 and the ink discharge port 106 are processed in advance. Substrate 101 and cover 10
4 and the meniscus forming member 103 on each ejection electrode 102, a minute slit-shaped ejection opening 107 is formed, and the ink supplied from the ink supply port 105 passes through the ejection opening 107 and passes through the ejection opening 107. The liquid is supplied to the distal ends of the meniscus forming members 103 protruding more outward, and the meniscus 108 is formed at the distal ends of the respective meniscus forming members 103.

[0003]

However, in the above-mentioned conventional electrostatic ink jet recording head, since the meniscus forming member 103 is formed using a photosensitive resist material, the thickness is several tens μm. Furthermore, since the meniscus forming member 103 is formed by exposure and development by photolithography, the corner at the tip of the meniscus forming member 103, which is the discharge point of the ink droplet 109, has a slack shape. Stable meniscus 10
8 cannot be obtained. Further, since the ink is not circulated near the tip of the meniscus forming member 103, the toner concentration in the ink at each ejection point varies, and excessive toner near the ejection point where ejection is not performed. There is a problem that concentration of particles occurs and ejection failure occurs during ejection.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention has been made in view of such a point. In an electrostatic ink jet recording head which discharges an ink droplet containing toner particles in ink by an electrostatic field, the object of the present invention is to provide An object is to stabilize ejection.

[0005]

According to the first aspect of the present invention,
The upper surface of each convex portion, or at least one of the wall surface of the convex portion and the bottom surface between the convex portions, of the substrate made of an insulating material processed into an uneven shape so that the convex portions are arranged at intervals,
A head substrate on which ejection electrodes made of independent conductive materials are formed, and a base plate for fixing the head substrate
When the distal end surface of the head substrate and is disposed so as to cover the bottom surface, and the ink receiving member to collect the overflowing ink from head substrate to the upper tip end opening of the other side of the head substrate It is disposed so as to cover the front by Rukoto
Ink cartridge that holds ink together with the base plate
And an upper cover that forms a member .

According to a second aspect of the present invention, in the first aspect, an ejection electrode is formed on an upper surface of each of the protrusions on the head substrate, and an interval between each of the protrusions of the head substrate is reduced. Are formed regularly at intervals of a desired resolution.

[0007] The invention described in claim 3 is claim 1 or 2.
Wherein the discharge electrode is covered with an insulating coating material.

According to a fourth aspect of the present invention, there is provided the method according to any one of the first to third aspects, wherein a width between adjacent convex portions has a width such that a capillary force can be generated. It is characterized in that it is formed so that the height is larger than the width between adjacent convex portions.

[0009]

Next, the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram of one embodiment of the electrostatic ink jet recording head of the present invention. FIG.
FIG. 1 is a cross-sectional view of one embodiment of an electrostatic ink jet recording head of the present invention. FIG. 3 is a configuration diagram of one embodiment of the recording head 1 of the present invention. The recording head 1 of the present invention includes a head substrate 4 on which ejection electrodes 3 for selectively applying a driving pulse to the ink 2 are formed, and an ink receiver for collecting the ink 2 overflowing from the head substrate 4. Member 5
And a base plate 6 for fixing the head substrate 4 at a desired position, and an upper cover 8 that is provided above the base plate 6 and forms an ink chamber 7 that holds the ink 2 together with the base plate 6. The head substrate 4 includes a substrate 9 made of an insulating material such as glass or ceramic, and a discharge electrode 3 made of a conductive material such as Ni or Cu.
Consists of The surface of the substrate 9 is processed into an uneven shape so that a plurality of convex portions 10 are formed at the same interval as the desired resolution, and the upper surface of each convex portion 10 has an ejection electrode 3 made of an independent conductive material. Are formed. The uneven shape on the surface of the substrate 9 is formed by processing such as dicing, laser processing, and isotropic etching, and the convex portion 10 having a high aspect ratio is formed. The width of the bottom surface 11 between the adjacent convex portions 10 and 10 has a width enough to generate a capillary force, and the height of the convex portion 10 is formed to be larger than the width of the bottom surface 11.

The ink receiving member 5 is made of an insulating material such as a plastic molded product, and has an end surface 4a and a bottom surface 1a located on the side of the ejection electrode 3 of the head substrate 4 which is the front end side.
1, and more specifically, a wall portion 5 </ b> A that is parallel to the front end surface 4 a and extends to a position higher than the bottom surface 11 is provided. And the ink receiving member 5
Is the ink 2 overflowing from the head substrate 4 together with the head substrate 4
An ink garter 12 for collecting the ink is formed inside. In addition, an ink outlet 13 for discharging the ink 2 collected in the ink garter 12 is formed below the ink receiving member 5, and the ink outlet 13 is connected to an ink tank (not shown) via a tube. Have been. The base plate 6 is made of an insulating material. On the surface of the base plate 6, electrode pads 14 for connecting to a drive driver (not shown) and a drive voltage input from each electrode pad 14 are supplied to each ejection electrode 3. Of the conductor 15 is formed. The head substrate 4 is a head substrate 4
Are disposed at desired positions on the base plate 6 such that the front end surface 4a of the base plate 6 projects outward with respect to the base plate 6, and each discharge electrode 3 and each conductor 15 are electrically connected by wire bonding or the like. It is connected to the.
The connection between the discharge electrode 3 and the conductor 15 and each conductor 15
It is coated and sealed with an insulating resin. Further, the base plate 6 may have a configuration in which a printed board or an FPC or the like on which a conductor pattern including the electrode pads 14 is formed is bonded to an insulating plate.

The upper cover 8 is made of an insulating material such as a plastic molded product, and is disposed above the base plate 6 to form an ink chamber 7 for holding the ink 2 together with the base plate 6. An ink supply port 16 for supplying the ink 2 into the ink chamber 7 is formed at an upper portion of the upper cover 8.
It is connected to an ink circulation pump (not shown) and an ink tank via a tube. A part of the upper cover 8 is disposed above the head substrate 4, and covers the upper part of the projection 10 at a position retracted from the front end surface 4 a of the head substrate 4. The ink 2 supplied from the ink supply port 16 to the ink chamber 7 is supplied to each of the convex portions 1 of the head substrate 4.
The ink 2 which is supplied to the front end side of the discharge electrode 3 through the flow path between 0 and 10 and overflows from the front end surface 4a of the head substrate 4 is collected by the ink garter 12 and collected from the ink discharge port 13 into the ink tank. You. The ink 2 collected in the ink tank is again supplied to the ink supply port 16 via the pump.

An opposing electrode 18 also serving as a platen for transporting the recording paper 17 is disposed in a direction opposite to the front end of the head substrate 4. In the portion, the corner 10a of the projection 10 is disposed so as to be closest to the counter electrode 18, and a minute discharge gap is provided between the corner 10a of the projection 10 and the counter electrode 18. . The recording paper 17 is a recording head 1
The gap between the discharge gap between the
Paper is fed along the top. The counter electrode 18 is always grounded to a zero level, or a constant negative bias voltage is applied. When the ink droplet 19 is ejected, a driving pulse voltage is applied to a desired ejection electrode 3 to generate an electric field between the ejection electrode 3 and the counter electrode 18, and the driven ejection electrode 3 is formed. A coulomb due to the concentration of the electric field is generated in the toner particles in the ink 2 forming the convex meniscus at the corner portion 10a of the portion 10, and the corner portion 10a of the convex portion 10 where the driven discharge electrode 3 is formed is discharged. As a point, an ink droplet 19 containing toner particles is ejected to the counter electrode 18 side, and printing is performed on the recording paper 17 on the counter electrode 18.

According to the recording head 1 described above, an uneven shape having a high aspect ratio is formed on the surface of the head substrate 4 and the space between the convex portions 10, 10 of the head substrate 4 is used as an ink flow path, thereby enabling ejection. A stable convex meniscus can be always obtained at the corner 10a of each convex portion 10 on the tip end side of the discharge electrode 3 of the head substrate 4 which is a point, so that the discharge of the ink droplet 19 can be stabilized. it can. In addition, the ink receiving member 5 is added to constantly circulate the ink 2 supplied to the corners 10a of the projections 10 on the tip end side of the discharge electrode of the head substrate 4 as the discharge points, so that the ink at each discharge point 2 can be prevented, and further, excessive concentration of toner particles near the ejection point where ejection is not performed can be prevented.

FIG. 4 is a schematic view of another embodiment of the head substrate 1 of the present invention. In this embodiment, the configuration of the discharge electrode 3 in the head substrate 4 of the embodiment of FIG. 1 is different, and the head substrate 4 of this embodiment is a substrate 9 made of an insulating material such as glass or ceramic. And N
The surface of the substrate 9 is formed into an uneven shape so that the projections 10 are formed at the same interval as the desired resolution. The discharge electrode 3 made of an independent metal material is formed on at least one of the opposing wall surfaces 10 b and 10 c and the bottom surface 11 of the portion 10.

[0015]

As described above, according to the present invention, an ejection point is formed by forming a concavo-convex shape having a high aspect ratio on the surface of the head substrate and using the space between each convex portion of the head substrate as an ink flow path. Since a stable convex meniscus can always be obtained at each convex portion on the front end side of the head substrate, the ejection of ink droplets can be stabilized. In addition, by adding an ink receiving member to constantly circulate the ink supplied to each projection on the tip end side of the discharge electrode of the head substrate serving as a discharge point, it is possible to prevent variations in the toner concentration in the ink at each discharge point. Further, it is possible to prevent excessive concentration of toner particles near the ejection point where ejection is not performed. Therefore, ejection of ink droplets can be stabilized.

[Brief description of the drawings]

FIG. 1 is a schematic view of an embodiment of an electrostatic ink jet recording head according to the present invention, wherein FIG.
(B) is a detailed view of a portion A in (a).

FIG. 2 is a cross-sectional view of one embodiment of the electrostatic inkjet recording head according to the present invention, taken along line BB in FIG. 1A.

FIG. 3 is a configuration diagram showing one embodiment of an electrostatic ink jet recording head of the present invention.

FIG. 4 is a schematic view of another embodiment of the head substrate of the present invention.

FIG. 5 is a perspective view of a conventional electrostatic ink jet recording head.

6A is a plan view of a head end portion of a conventional electrostatic ink jet recording head, and FIG. 6B is a cross-sectional view taken along line CC in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Recording head 2 Ink 3 Discharge electrode 4 Head substrate 5 Ink receiving member 6 Base plate 7 Ink chamber 8 Upper cover 9 Substrate 10 Convex part 11 Bottom surface 12 Ink garter 13 Ink discharge port 14 Electrode pad 15 Conductor 16 Ink supply port 17 Recording paper 18 Counter electrode 19 Ink drop

Continuing on the front page (72) Inventor Tadashi Mizoguchi Niigata Prefecture Kashiwazaki-shi Oaza 7546 Yasuda Niigata Nippon Electric Co., Ltd. 72) Inventor Hitoshi Takemoto 7546 Yasuda, Oji, Kashiwazaki-shi, Niigata Inside Niigata Nippon Electric Co., Ltd. Toru 7546 Yasuda, Kashiwazaki-shi, Niigata Prefecture Niigata Nippon Electric Co., Ltd. (56) References JP-A-62-227755 (JP, A) JP-A-57-185160 (JP, A) JP-A-58-217375 ( JP, A) JP-A-55-100160 (JP, A) JP-A-58-14761 (JP, A) JP-A-55-111270 (JP, A) JP-A-58-82765 (JP, A) Hei 7-186434 (JP, A) (58) Fields surveyed (Int. Cl. ⁶ , DB name) B41J 2/385 B41J 2/06

Claims (4)

(57) [Claims] At least one of a top surface of each projection, or a wall surface of the projection and a bottom surface between the projections, of a substrate made of an insulating material processed into an uneven shape so that the projections are arranged at intervals. A head substrate on which discharge electrodes made of independent conductive materials are formed, a base plate for fixing the head substrate, and a front end surface and a bottom surface of the head substrate. an ink receiving member to collect the overflowing ink from head substrate to the, together with the base plate by Rukoto head opens the front end side of the substrate is disposed so as to cover the upper portion of the other side
An electrostatic ink jet recording head, comprising: an upper cover that forms an ink chamber for holding ink . 2. An ejection electrode is formed on an upper surface of each projection on the head substrate, and intervals between the projections of the head substrate are regularly formed at intervals of a desired resolution. The electrostatic ink jet recording head according to claim 1, wherein: 3. The electrostatic ink jet recording head according to claim 1, wherein the discharge electrode is covered with an insulating coating material. 4. The method according to claim 1, wherein the width between the adjacent protrusions is such that a capillary force can be generated, and the height of the protrusions is larger than the width between the adjacent protrusions. The electrostatic ink jet recording head according to any one of claims 1 to 3, wherein